Go through these in order and stop at the first one that applies. If you are reading this for someone else, answer for them.
1
Is any of this happening now?
Call 911
Call emergency services if you have:
Severe or rapidly worsening trouble breathing
Blue, grey or unusually pale lips or skin
New confusion, fainting or difficulty staying awake
Severe chest pain with sweating, collapse or a feeling of pressure
Signs of severe infection, such as very fast breathing with cold or mottled skin
Other emergency signs, for anyone
Someone who is struggling to breathe, gasping, choking, or cannot get words out
Someone who has chest pain, tightness or pressure lasting more than a few minutes
Someone who has sudden weakness or drooping on one side of the face or body, slurred speech, or sudden confusion
Someone who is unconscious, or cannot be woken
Someone who is bleeding heavily and it will not stop with firm pressure
Someone who has had a seizure that will not stop, or does not wake up afterwards
Someone who has lips or skin that look pale, blue, grey or blotchy
Someone who you believe has taken an overdose or swallowed something poisonous
2
Is any of this happening?
Be seen today
These symptoms can indicate low oxygen, sepsis or another urgent condition.
Seek urgent medical assessment the same day if you have pneumonia and develop worsening breathlessness, persistent fever, increasing one-sided chest pain or a clear decline after starting to improve.
3
Does any of this apply?
Book an appointment
If you are recovering at home, arrange routine follow-up if cough, tiredness or breathlessness is not gradually improving.
Also contact your care team if a previous chest-tube or surgical site becomes increasingly red, swollen, painful or starts leaking fluid.
Every sign above is quoted from the sofidex article on Parapneumonic pleural effusion. If you are not sure, err upward — it is always reasonable to be checked.